Environmental implications of China’s wind-coal combined power generation system

Abstract

China’s power supply structure is dominated by coal-fired power. As China’s renewable power expands, coal-fired power units are required to improve flexibility to balance power system. However, more flexible operation of coal power units increases energy consumption and pollutant emissions. This paper examines the energy efficiency, CO2 and pollutant emissions characteristics of China's generic wind-coal combined power generation system, and discusses pollution-minimizing dispatch strategies by modeling three hypothetical scenarios of wind-coal combined power generation systems. For day-scale analyses, we find expected displacement rates of coal consumption and CO2 emission decrease by wind fraction rate, indicating reduced energy savings from wind power per unit of increase in wind capacity. For NOx emission, we find that expected displacement rate reaches maximum value of 112% when wind fraction rate is equal to 0.27.For week-scale analysis, we simulate the coal consumption rate and emission factors with and without an operation of shutdown and startup of coal power units in the system. We suggest future study on dispatch decisions of startup/shutdown of coal power units to optimize power generation economically and environmentally.